Fluid pressure brake



,E. A. RQQKWELL FLID PRESSURE .BRAK

y vFiled Dec. 14, '1927 Wsw Patented Apr. 10, 1934 V UNITED STATES PATENT OFFICE My invention relates particularly to a brake mechanism involving the application of fluid pressure vfor the operation thereof, and has especial adaptation for use in automobile brakes.

My present invention is an improvement upon the subject matter of my application 'upon a Fluid pressure brake, Serial Number 233,828 filedV on the 9th day of December, 1927, now Patent No. 1,896,374, granted Feb. 7, 1933.

10 Whereas the said application relates to a brakl ving mechanism operated by vacuum, the present application involves thepuse of fluid pressure above the atmospheric pressure. The advantages Vwhich inhere in the device of my application aforesaid, .also apply to a very large extent, to

the mechanism of the present application.

The object of my invention is, therefore, to provide a uid pressure operated brake applying means in which the braking effect is controlled by variations in the power applied both on the pressure-applying and pressure-releasing movements, so that, in veiect, the pressure will be shut oi at any particular point in the release of the pressure control up to .a certain maximum, as

well as in the application of the pressure control. This provides an instantaneous control of the mechanism. v

`Further objects of my invention will appear from the detailed description of ,the same hereinafter.

While my invention is capable of embodiment in many different forms, for the purpose of illustration I have shown only one form in the ac companying drawing, in which:

of the pressure Voperated brake applying means.

Figure 2 is a front elevation of the casing containing tne pressureoperating mechanism with the cover and parts carried thereon removed.

Figure 3 is a vertical sectionrof a detail of the Vpedal connection. e

In Figure 1 the shaft 14 is the throttle-actuating shaft and at one end of the shaft 14, there is an arm, 17, which is approximately U-shaped, and the other end of which is connected by a pivot, 18, to a foot pedal, 19, supported above a oor "board, 20, vof the automobile. The upper end of the lever 17, passes through an opening, 21, in the floor board. In order that the throttle may be operated not only by the foot pedal, but also from the steering column, there is provided a l lever, 22, on the end of the shaft, 14, upon which it is loosely carried in such manner as to allow a limitrof angular play between theleyer, '17, 5.5 and the lever, 22.

Figure 1 is a vertical section of the details` The other en d of the pedal, 19, has near the heel of the same a pivot, 30, connected to a link, 31, which passes through a housing, 32, iii the oor board, 20. An amount of play between the pedal, 19, and the link, 3l, is provided by means of a slot, 32a, in the link, 31, through which. the pivot, 30, passes, so that the latter rests upon a plug, B2b, pressed upwardly by a spring, 32. The

other end of said link, 31, is connected to a pivot,

33, on a link, 34, which is also'pivoted to the U-shaped lever, 17. The said pivot, 33, also makes pivotal connection of both links, 31 and34, with the end of a short lever, 35, on a shaft, 36.

To a pivot, 37, on the lower part of lever, 35, near its fulcrum on the shaft, 36, there is attached one end of a stretched spring, 38, whose other end is attached to the engine body as seen at 38, so .that the spring reacts to restore the foot pedal, 19; and said pivot, 37, is also connected to a screw-threaded rod, 39, which has a screwthreaded attachment for an adjustable connec-v tion to a rod, 40, which latter rod is pivotally connected at its rear end to a lever, 41, supported on a pivot, 42, carried on the face of a cover plate, 43. The lever, 41, is connected at its lower end by plunger, 44, which extendsthrough said cover plate, 43, a packing, 45, held in place by a retainer, 46, being provided around said plunger at its sliding bearingin said cover plate.' Inside the cover plate 43, a lever 47 is pivotally connected by pin 47a to the plunger 44, the pinl 47a tting in an elongated slot 44a in the plunger. At about the middle point of its length the lever, 47, is connected by a pivot, 49, to the stem, 50, of a valve, 51which co-operates with the valve seat, 52, in an inner valve casing, 53, which is adapted to be received in an outer valve casing, 54, whichlatter casing is carried in a chambered casing, 55, of which the chamber, 96, is to serve as the reservoir for the super-atmospheric fluid pressure by which braking devices are to be applied as hereinafter described. A packing ring, 56, makes a tight joint between the valve casings, 53 and 54, and a retainer ring, 57, holds the packing ring, 56, in place. lA further packing ring, 58, is located between the valve casings at the rear end of the casing, 53, for the same purpose. At its inner,-rear,-end the valve stern, 50. is connectedto a diaphragm, 59, which is held in'place by a clamping ring, 60, secured by screws, 61. At its upper end the Ilever, 47, has a slot, 62, for making pivotal connection with pin 62a of another valve stem, 63, which, at its rear end,` carries the valve, 64, co-operating with the valve seat. 65, in the outer valve casing, 54.

It will be noted that there is a tendency for the valve, 51, to be unseated due to the pull of a spring, 66, which is stretched between the lever, 47, and the removable plug, 67, at the rearside of the casing, 54, and operates for stressing the lower end of the lever, 47, rearwardly, tending to hold its pivotal connection to the plunger, 44, as seen at 47, at the rear end of the slot, 44, in the plunger, 44. The forward end of the valve rod, 63, is connected to a diaphragm, 68, which is held in place by a clampingring, 69, on the outer valve casing, 54. The forward face of this diaphragm, 68, is always in communication with the outer air through a port, 70, in the cap, 43.

Superatmospheric fluid pressure is supplied to the chamber 96 through pipe 75 leading from a suitable source of high pressure fluid supply. The capacity of the pressure reservoir 96 is sumciently large so that when pressure therefrom is admitted to the brake actuating device, it operates promptly for applying the brakes. This pressure reservoir, 96, is arranged so that the pressure may come into action by passing the port controlled by the valve. 64, port 98, into the chamber, 97, of the casing, 54, and thence through passage 99, to a piston cylinder, 100, having therein a piston, 101, provided with a leather packing ring, 102, held in place by a disk spring, 103, carried on the piston to which it 'is held by the piston rod, 104, which passes through leather packing, 105, held in place by ring, 106, and a cotter pin, 107, fastened on a cover, 108, secured to the casing, 55, by. screws, 109. -The protruding end oi' the piston rod 104 is adapted for suitable connection to the customary brake linkage for applying the wheel brakes of the vehicle with which the apparatus is associated. The forward face of the piston, 101, is always exposed to atmospheric pressure through a port, 110, to which there is connected a tube, 1.11, extending in a housing, 112, enclosing a chamber, 113, containing air filtering material, 115, and having air inlet ports, 114.

The release of the pressure on the piston, 101, is effected by opening the valve, 51, which vents to a greater or less degree the chamber, 97.

It will be understood that the forward face of the diaphragm, 68, and the rear face of the diaphragm, 59, are exposed to atmospheric pressure, the former directly in the chamber of the cap, 43, andthe latter through a port, 115, communicating from the cavity of the cap, 43, past the mounting of the diaphragm. 59, to the rear side thereof.

It will be understood that whatever the access for pressure from the pressure source to the chamber, 100, in the absence of leak or ventfor pressure from the piston chamber, the pressure therein will equal that maintained at the pressure source, variation in the sise of the opening for access having only the eifect of varying the time necessary for the pressure to become thus equaliaed. The purpose oi' the present invention being to cause the 'pressure operative in the piston chamber to vary in degree according to the variation of pressure applied to the at-will-operated-controlling means. it is necessary to provide some means in addition to or other than mere variation in the degree of opening of the port ci' access of the pressure to the piston. For this purpose two methods are available, to wit, leither to provide a vent or outlet for the pressure fluid,

the .ratio oi' whose area tothe area of the inlet will determine the proportion'of the pressure l,available at the pressure source which will be obtained in the chamber, 97, and thereby in the piston cylinder, or to provide means by which after the fluid pressure has been admitted, the inlet shall be closed when the pressure reaches a predetermined degree. The latter method is much preferred because of avoiding the waste of fluid pressure which is involved in the nrst method, and said latter method is employed in the construction described and may be understood upon considering' the operation as follows:

Assuming the parts at rest position and the chamber, 96, in communication with the source of superatmospheric pressure, if the lever, 41, is actuated by its connection withthe pedal for retracting the rod, 44, for operating the lever, 47, the latter lever for the instant fulcrums at 62e on the valve stem, 63, (the valve, 64, being held seated by the pressure in the chamber, 96) and pulls the valve, 51, to its seat at the port, 52; whereupon the pivot, 49, by which thelever, 47, is connected' to the stem of the valve, 51, becomes the fulcrum of the leverr 47, whose further movement opens the valve, 64, against the pressure in the reservoir, 96, and admits the fluid pressure to the chamber, 97, where it operates on the diaphragm, 66, tending to close the valve. 64, which will accordingly be closed as soon as the pressure admitted past said valve is suilicient to overcome the force applied through the pedal connections to the lever, 47, in the direction for holding the valve, 64, open. The fluid pressure in the chamber 97 also acts upon the diaphragm 59 tending to open the valve 51 after the valve 64 has been closed. Thus it will be seen that the pressure admitted and operating on the piston, 101, in the cylinder, 100, is determined by the pressure with which the operator holds the heel of the pedal depressed, and that, accordingly, the braking pressure derived from the source of super-atmospheric pressure-whether it be the engine or separate air compressing device,will be varied in accordance with the variation from time to time of the pressure applied by the operator upon the pedal.

Similarly, when the operator desires to release thev brake, upon releasing the pressure on the pedal, and reducing the force acting on the lever, 41, against the pressure which holds it stressed against the resistance vof the spring, 66, and in the direction for holding the valve, 5l, seated, the spring, 66, retracts the lever, 47, and opens the valve, 51, permitting the venting of the pressure in the chamber, 97, and thereby in the piston chamber, 100, until that pressure is reduced to correspond to the pressure operating from the pedal on the.1ever, 47; whereupon that lever yielding to the pressure at the pedal, seats the valve, 51, retaining the fluid pressure operative on the piston, 101, at the reduced degree corresponding to the reduced pressure applied by the operator upon the heel ofthe pedal.

In the operation of the apparatus described the brake mechanism comes into braking position as shown in Figure 3, upon the operation of the pedal by the pressure of the foot of the operator upon the heel of the pedal, 19, thrusting downward the link, 31, to a greater or less degree, according to the amount of pressure applied, because the resulting movement of the lever, 35, must stretch the spring, 38, accumulating its resistance proportionately to the movement by which it is stretched. The movement for stretching the spring, 38. produced by depressing the heel of the pedal, is communicated through the link, 39 and 40. and lever, 41, to the thrust plunger, 44; and thence to the lower end of the valve-operating lever, 47, the slight lost motion in the slot, 44a, provided for the pivot, 47a, being rst absorbed, and the lower end of the lever, 47, being then pulled forward against the resistance of the spring, k66. At this stage it will be noted, as already described, that the valve, 64, is held seated by the pressure in the reservoir, 96, and in consequence thepivot, 62a, at the forward end of the stem of said valve, 64, becomes the fulcrum of the lever, 47, which, therefore, in the first part of the movement produced by the plunger, 44, pulls the valve, 51, forwardly to its seat, 52. Thereupon the pivot, 49, on the stem, 50, of the valve, 51, becomes the fulcrum for the lever, 47, and the continuing forward pull of the plunger, 44, on the lower end of the lever rocks the upper end of said lever rearwardly, forcing the valve, 64, open, admitting the fluid pressure to a degree corresponding to the pressure applied to the pedal as already explained. And it will be seen that there thus results from the depression of the pedal to a degree dependent upon the pressure applied, a limited access of fluid pressure to the piston cylinder, 100, proportionate to the pedal pressure and pedal movement, but as many times greater than that pressure as the pressure in the chamber, 96, admitted to the chamber, 97, past the valve, 64, exceeds the -amount of pressure necessary to open the valve.

.Approximately therefore, the ratio of the pressure for operating the brakes derived from the super-atmospheric pressure source to the pressure applied by the operator to the heel of the pedal is the ratio of the area of the piston, 101, to the area of the valve, 64.

And as above explained, whatever be the position in which the piston, 101, may be moved upon the admission of the super-atmospheric pressure to the piston cylinder for operating the brakes, the reverse action of the operator relaxing the pressure on the pedal which operated for opening the valve, 64, will cause reverse action of the piston, since the reaction of the spring, 38, upon the release movement of the pedal will be equal to the force applied for stretching itupon the depression of the pedal which is the measure of the force applied by the operators foot for openwhich the pressure on the piston cylinder forV holding the brakes set will be released, will be proportional to the extent to which the pedal is released, 4permitting the reaction of the spring,

38, to an extent measured by the releasing movement of the pedal. In other words, when any given amount ofv foot pressure Within a predetermined maximum determined by the resistance of the spring, 38, is released, this will cause the plunger, 44, -to unseat the valve, 51, and hold it unseated until only a certain amount of pressure .remains in the chamber, 97, the pressure released being vented past the valve, 51, to the same degree at any given position of the pedal, whether that' position was reached by depressing the pedal from rest position or by releasing it for return from a more depressed position.

While I have described my invention above in detail, 1 -wish it to be understood that many changes may be made therein without departing from the spirit thereof. f

I claim: 1. In a structure for the purpose indicated, a device operated by super-atmospheric pressure, a source of fluid pressure; a conduit therefrom to the4 super-atmospheric fluid-pressln'e-operated device, said conduit comprising a chamber havving a port of communication withl the fluid pressure source, and a valve seating at said port-in the direction of flow of fluid pressure from said source, the chamber wall comprising a diaphragm exposed interiorly to the pressure admitted into the chamber and exteriorly to atmospheric pressure, said diaphragm being connected with the valve for seating the latter by the movement caused by the fluid pressure on the diaphragm admitted past the valve when open, means exterior to said chamber and conduit for actuating the valve, and means positively operable by pressure applied varyingly at will to said exterior means for opening and holding open the valve against the action of the diaphragm for closing it; whereby the valve is held open only until the pressure admitted for acting interiorly on the diaphragm is adequate to overcome the pressure applied at will.

2. A construction for the purpose indicated' comprising a chamber having a movable wall rendering it expansible and reducible and adapted to be connected with a source ofl super-atmospheric fluid pressure; brake-operating 'means adapted to be operated by said moving wall;

means for controlling the admission of superatmospheric fluid pressure to said chamber, said chamber having a vent port, a valve controlling said port, and a diaphragm exteriorly exposed to atmosphere pressure and interiorly to the uid pressure admitted to said chamber, said diaphragm being operatively connected with the vent valve for opening it by movement ofthe diaphragm by the fluid pressure Within the chamber, and exterior means operable by pressure applied at will for positively holding the vent valve `closed against said means tending to open it; whereby the pressure in said chamber may be vented to any degree by relaxing the pressure applied at will for holding the vent' valve closed.

3. A structure for the purpose indicated comprising brake-operating means adapted to be operated by super-atmospheric fluid pressure and adapted for connection .with a source of such pressure;4 an inlet valve controlling the admission of said pressure to the brake-operating means, a diaphragm exposed to the pressure admitted by the opening of the valve operatively associated with the latter for closing it by said admitted pressureisaid chamber having a vent port and a valve controlling said port arranged with relation tosaid port for being seated by the pressure, and a diaphragm exposed to the admitted pressure 4operatively associated with the vent valve for opening the latter by said pressure; means exteriorly operable at will for controlling said valves to admit or 4vent the pressure to the desired degree. e

4. A structure ,for the purpose indicated comprising a piston cylinder and a brake-actuating piston therein, a source of Ysuper-atmospheric liuid pressure, a conduit from said source to the piston cylinder, valve means controlling admisthe valve, adapted to lbe moved by said pressure' and operatively connected to the valve for closing the sameby the movement of said element caused by the pressure admitted past the valve, and means positively operable by pressure applied varyingly at will for holding said valve open, the area of the piston being a relatively large multiple of the area of the element exposed to fluid pressure for operating the inlet valve; whereby the braking pressure is a correspondingly large multiple of the pressure applied at will for opening the inlet valve.

5. In an apparatus for doing work by fluid pressure, av source of super-atmospheric fluid pressure, work-performing means adapted to be operated by said super-atmospheric pressure, a

pressure communicating passage between said.

source of fluid pressure and said work-performing means, controlling means operable in normal position to close said pressure communicating passage against the admission of the super-atmospheric iiuid pressure to said work-performing means and to vent said work-performing means to the atmosphere, means associated with said .controlling means mounted in sealing relation vwith said pressure communicating passage and operable upon the admission of said super-atmospheric pressure to said work-performing means\to oppose the movement of said controlling means in a direction for actuation of said work-performing means and manually operable means positively connected to said controlling means outside of said pressure communicating passage for variably controlling the actuation of said work-perforrning means in accordance with the pressure applied.

6. In an apparatus as described in claim 5', said controlling means comprising a pair of valves,

` one of which is a pressure controlling valve seating in the direction of flow of the fluid pressure to said work-performing means and the other of said valves being a normally open venting valve mounted to seat in a direction against the venting of pressure from said work-performing means. y

7. In an apparatus as described in claim 5, said controlling means comprising a pair of valves, one of which is a pressure controlling valve seating in the direction of flow of the fluid pressure to said work-performing means and the other of said valves being a normally open venting valve mounted to seat in a direction against the venting of pressure from said work-performing means, and said means in sealing relation with the' passage comprising a diaphragm associated with each valve subjected on one side to the fiuid pressure acting against said work-performing means and on the other side to atmospheric pressure.

8. In a device of the character described, a super-atmospheric fluid pressure reservoina brake actuating cylinder, a piston movable in said cylinder, a communcating passage between said reservoir and s aid brake actuating cylinder, a normally closed valve for controlling the admission of super-atmospheric fluid pressure to said brake actuating cylinder, a normallybpen venting valve arranged to vent the pressure from said brake actuating cylinder, a diaphragm secured to each of said valves and sealing said pressure communieating passage, each of said diaphragms being exposed on the exterior to atmospheric pressure and on the interior to the super-atmospheric pressure developed in the brake actuating cylinder and arranged such that the differential pressure upon each of said diaphragms tends to move the correspending valve to its normal position and means connected to each valve outside of said pressure communicating passage 'arranged to be variably operable to positively move said valves for actuation of said piston whereby the pressure applied to said variably operable means determines the braking pressure during application and release.

9. In a device of the character described, a super-atmospheric fluid pressure reservoir, a pressure-receiving chamber, work performing means operative by super-atmospheric pressure derived from said chamber, a valve controlling, the admission of iiuid pressure from said reservoir to said chamber, a second valve controlling the flow of fluid pressure from said chamber to the atmosphere, resilient means operative to normally seat said rst valve and open said second valve and positively operable means controllable by the operator for initially closing said second valve and subsequently variably opening said first valve, said resilient means being operative upon relaxation of pressure applied to said positively operable means to initially close said first valve and subsequently variably open said second valve.

1 0. In a device of the character described, a super-atmospheric fluid pressure reservoir, a pressure receiving chamber, work performing means operative by super-atmospheric pressure derived from said chamber, a valve controlling the admission of fluid pressure from said reservoir to said chamber and arranged to seat in the direction of flow of the fluid pressure, a second valve controlling the fiow of fluid pressure from the chamber to the atmosphere and arranged to seat in the direction of flow of the fluid pressure, a diaphragm forming a movable wall of said chamber and secured to said first valve whereby the pressure in said chamber acting upon said diaphragm tends to move said first valve to seated position, a second diaphragm forming a movable wall of said chamber and secured to said second valve whereby the pressure in said chamber acting upon said second diaphragm tends to move said second valve to normally open position, resilient means operative to normally seat said first valve and open said second valve and positively operable means controllable by the operator for initially closing said second valve and subsequently variably opening said first valve whereby the pressure produced in said chamber together with the effective fonce of said resilient means oppose the pressure applied to saidl positively operable means and tend to close said first valve and variably open said second valve.

11.,In a device of the character described, a super-atmospheric fluid pressure reservoir, a pressure-receiving chamber, work performing means operative by super-atmospheric pressure derived from said chamber, a'valve controlling the admission of fluid pressure from said reservoir to said chamber, a second valve controlling the escape of iiuid pressure from said chamber to the atmosphere, a lever pivotally connected at spaced points to each of said valves, resilient means acting upon said lever to normally seatsaid first valve and open said second valve and mechanical linkage connected to said lever for initial p ositive closing movement of said second valve and subsequent positive variable opening of said first valve whereby the degree of movement of said linkage is always proportionate to the movement of said 

